EP0692099A1

EP0692099A1 - Phase testing device

Info

Publication number: EP0692099A1
Application number: EP95908896A
Authority: EP
Inventors: Martin Schuster; Gottfried Fischer; Wolfgang Georgi
Original assignee: Pfisterer Kontaktsysteme GmbH; Karl Pfisterer Elektrorechnische Spezialartikel GmbH and Co KG
Current assignee: Pfisterer Kontaktsysteme GmbH
Priority date: 1994-02-02
Filing date: 1995-02-02
Publication date: 1996-01-17
Anticipated expiration: 2015-02-02
Also published as: ATE228251T1; DE4403059C1; DE59510461D1; EP0692099B1; WO1995021385A1

Abstract

A phase testing device, in particular for medium and high voltage networks, has contacting means, a test circuit (9, 10) that may be connected to an internal current source, and a display means (14, 15) for displaying a phase balance or unbalance. The phase testing device is designed with a single pole. The contacting means have only one testing electrode whose voltage signal is applied to the input of the test circuit (9, 10). The test circuit (9, 10) contains a simulator that continues to simulate the voltage phase position of the conductor that has been first contacted, after the contact period. The test circuit (9, 10) further contains a comparator that compares said phase position of the conductor that has been first contacted with the voltage phase position of the conductor that is next contacted, and that supplies a signal based on this comparison to the display means (14, 15).

Description

description

Phase tester

The invention relates to a phase test device, in particular for medium and high voltage networks, with a Kontaktiereinrich¬ device, a test circuit that can be connected to an internal power source, and a display device for displaying a phase or phase inequality.

The known phase testers of this type are two-pole testers. The contacting device has two test electrodes, each of which is arranged at one end of an insulating rod. One of these two isolating rods carries the test circuit, the internal current source and the display device. The other test rod is connected to the test circuit via a connecting line. This connecting line complicates the use of such phase test devices.

The object of the invention is therefore to create an improved phase test device. This problem is solved by a phase test device with the features of claim 1.

The single-pole design of the phase test device according to the invention considerably improves handling and is also advantageous for safety reasons. The single-pole Formation of the phase tester that the two conductors, the voltages of which are to be compared with respect to their phase position, can only be contacted one after the other in time. Thanks to the simulation device for the phase position of the voltage of the first contacted conductor beyond the contacting time, the test circuit can compare the phase position of the voltage of the subsequently contacted conductor with the phase position of the first contacted conductor and, based on this comparison, control the display device accordingly.

In a preferred embodiment, the test circuit contains a microcontroller that performs the functions of the simulation device and the comparison device.

The test circuit preferably has input electronics which, at the inputs of the microcontroller, apply logic signals for the presence of a voltage signal from the test electrode, the supply voltage for the test circuit and the display device, and a square-wave signal synchronized with the zero crossings of the voltage signal generated by the test electrode .

In order to take energy from the internal current source only when a test is being carried out, a manually operable switch for connecting the test circuit to the internal current source and a switch-off device which switches off the current source when it is at the input for a predetermined period of time are expediently provided the test circuit has no voltage signal. The microcontroller preferably also performs the function of the shutdown device.

With the help of the microcontroller, the functionality of the phase test device can also be tested, which is in front of everyone ability of the phase test device to be tested, which is necessary before each phase test. For this purpose, the microcontroller can have a memory with a test program, which is called up by closing the manually operable switch.

In a preferred embodiment, the test circuit has a device by means of which the frequency, preferably several times at predetermined time intervals, is measured both during the contacting of the first conductor and the contacting of the second conductor and which interrupts the phase test in the event that the measured Frequencies are outside a predetermined frequency range. A device of the test circuit for determining the frequency change is preferably also present both during the contacting of the first conductor and during the contacting of the second conductor. This device also causes the phase test to be terminated in the event that the difference between the two frequency change rates is greater than a predetermined value.

Finally, there is advantageously also a device for calculating the best-fit line indicating the relationship between time and frequency.

The microcontroller can also perform the functions of all of these devices.

The invention is explained in detail below using an exemplary embodiment shown in the drawing. Show it

1 shows a schematically illustrated view of the exemplary embodiment,

2 shows a plan view of the underside of the housing containing the electronic components,

3 is a block diagram of the embodiment;

4 shows a frequency-time diagram for the frequency measurements,

Fig. 5 shows the state diagram of the embodiment

A phase test device for medium and high voltage networks, by means of which it can be determined whether the voltages of two conductors in such a network are in phase or different in phase, has, as shown in FIG. 1, at the upper end of a selective tip 1 which eliminates interference field inclusions and contains in its interior, for example, a safety resistance chain, a test electrode 2, by means of which the conductors to be tested are contacted. An insulating rod 3 can be coupled to the lower end of the selective tip 1, the lower end of which carries an insulating handle 4. Two screens 5 and 6 are arranged on the insulating rod 4 in such a way that they mark the protective distance or the area which must not be overlapped.

In the area of the lower end of the selective tip 1, a radially protruding support arm 7 is fixed thereon, the downward-angled end section of which carries a housing 8. As shown in FIG. 3, this housing contains input electronics 9, a microcontroller 10 and a battery, which are electrically connected to the lower end of the safety resistance chain. A front plate 11 (FIG. 2) forming the underside of the housing 8 bears a manually operable switch 12 as well as a yellow light-emitting diode 13, a green light-emitting diode 14 and a red light-emitting diode 15. By means of the switch 12, the input electronics 9, the microcontroller 10 and the three diodes are connected to the battery. The switch 12 can also be controlled electronically so that it can be brought into its non-conductive state by the microcontroller 10.

The input electronics 9 generate a logic one signal based on the voltage signal of the test electrode 2, provided that the conductor contacted by the test electrode 2 is live. Furthermore, the input electronics 9 generate a logic one signal when the supply voltage of the battery is sufficient for the phase test device to operate properly. Finally, the input electronics 9 generate a square-wave signal due to the zero crossings of the voltage supplied by the test probe. 3, this square-wave signal is applied to two inputs of the microcontroller 10. Two other inputs are connected to the outputs of the input electronics 9 for the two logic signals. The LEDs 13 to 15 are each connected to one of the outputs of the microcontroller 10. Another output leads to switch 12.

By manually switching on the switch 12, a function test is first carried out. For this purpose, a test program is called up from a memory of the microcontroller 10. The yellow light-emitting diode 13 lights up when the phase tester referred to below as the phase tester is fully functional and ready for operation. The lighting up of the yellow light-emitting diode 13 also represents the request to the user of the phase tester to contact the first conductor with the test electrode 2. If the first conductor carries an AC voltage, then the input electronics 9 generate a logic one signal. In addition, it generates the square-wave voltage already mentioned, its rising edges with the zero crossing from the negative to the positive half-wave and its falling edges with the Zero crossing from the positive to the negative half-wave are synchronized. When the test as to whether the conductor carries an alternating voltage has been completed, a timer is started which determines the duration for twenty periods of the alternating voltage, on the basis of which the frequency f _{n is} determined. If this frequency f _{n is} greater than 50.1 Hz or less than 49.9 Hz, the microcontroller 10 terminates the entire measurement. The yellow light-emitting diode 13, which has gone out at the start of contacting the first conductor, now lights up again. If, on the other hand, the frequency f _η lies within the frequency range mentioned, a second frequency measurement is carried out two seconds after the end of the first frequency measurement. Here too, the frequency f is determined from the period of twenty periods. This frequency is then also checked by the microcontroller 10 whether it lies outside or within the permissible frequency range. In the former case, the microcontroller 10 stops the measurement, in the latter case the frequency change that may be present is determined. If it is greater than 3 mHz per second, the microcontroller 10 stops the measurement. If it lies within this value, then the yellow light-emitting diode 13 starts to flash, which means that the user is now asked to contact the second conductor.

During the contacting of the first conductor, the course of its alternating voltage is simulated by the microcontroller 10, at least with regard to the zero crossings. This simulation is continued by simulation even after the contact has ended.

After the determination of the frequency of the voltage of the first conductor and its frequency change has been completed, the operator is prompted by a flashing of the yellow light-emitting diode 13 to contact the second conductor. If this contact is not made within a predetermined period of time, which in the exemplary embodiment is 10 seconds, the measurement is terminated. If the contact is made within the predetermined time voltage and the second conductor carries an alternating voltage, then the frequency is determined twice from the period of twenty periods, as with the first conductor, at intervals of 2 seconds. It is also checked whether the measured frequency is within the permissible frequency range. The frequency change is also determined and compared with the permissible limit value.

If the test has been carried out properly by this point in time, it is checked whether the difference between the frequency change in the voltage of the first conductor and the frequency change in the voltage in the second conductor is equal to or less than 3 mHz / s. If this condition is not met, the ^" measurement is aborted. In the event of compliance, a simplified compensation calculation is first carried out by the microcontroller 10. With t ₊ tf ₊ f * 31 ⁺ * 22 ^f 2 ^{+ f} 3

-J- * _ ¹ f * _ ± _ 4- * _ ^* * ^υ 2 2 2 2

where f _Q to f "mean the frequencies determined in the four successive frequency measurements and t, .., t _Q p, t" ₁ and t the times indicated in the diagram according to FIG. 4, for the dependency the equation following the frequency is formed by time

f ₌ V - ^f 0 ^* _(t _ _t *) _{+ f *} t * - * ^uu ^τ l ^t 0

which is also referred to as a straight line.

Assuming that a linear frequency change in accordance with this equation has occurred, the microcontroller 10 then, due to the phase position of the alternating voltage of the first conductor, which it simulates, for example with the aid of an oscillating circuit, and the phase position of the voltage of the second conductor Phase shift determined. If this phase shift is smaller than a predetermined limit value, which in the exemplary embodiment is 30 °, the green light-emitting diode 14 lights up because it can then be assumed that the two conductors belong to the same phase of the network. However, if the phase shift is greater than the limit value, the red light-emitting diode 15 lights up as a sign that the two conductors belong to different phases of the network. This display ends after two seconds. The yellow light-emitting diode 13 then lights up again, as a sign that the next test can be carried out. If an AC voltage signal is not present again at the input of the microcontroller 10 within a minute, the switch 12 is opened.

Claims

Patent claims

1. phase testing device, in particular for medium and high voltage networks, with a contacting device, a test circuit which can be connected to an internal power source, and a display device for displaying a phase equality or phase inequality, characterized in that a) the device is of single-pole design and the contacting device has only a single test electrode (2), the voltage signal of which is present at the input of the test circuit (9, 10), b) the test circuit (9, 10) is a simulation device for the phase relationship of the voltage of the conductor contacted first beyond the contacting time, and c) the test circuit (9, 10) contains a comparison device which compares the phase position of the conductor contacted first by the simulation device with the phase position of the voltage of the conductor contacted second and a comparison based on this comparison Signal to the display device (13 bi s 15) delivers.

2. Phase test device according to claim 1, characterized in that the test circuit (9, 10) has a microcontroller (10) which forms the simulation device and the comparison device.

Phase test device according to claim 2, characterized in that the test circuit (9, 10) has input electronics (9) which, at the inputs of the microcontroller (10), provide logic signals for the presence of a voltage signal of the test electrode (2), the supply voltage for the test circuit (9, 10) and the display device (13 to 15) and a square wave signal synchronized with the zero crossings of the voltage signal.

4. phase test device according to one of claims 1 to 3, marked by a manually operable switch (12) for connecting the test circuit (9, 10) to the internal current source (16) and a switch-off device which switches off the current source (16) if no voltage signal is present at the input of the test electrode (2) for a predetermined period of time.

5. phase tester according to claim 4, characterized in that the microcontroller (10) also forms the shutdown device.

6. phase testing device according to one of claims 2 to 4, marked by a memory of the microcontroller (10) from which a self-test program can be called up by closing the manually operable switch (12).

7. phase test device according to one of claims 1 to 6, marked by a device of the test circuit (9, 10) for frequency determination, preferably for repeated frequency determination at a predetermined time interval, both during the contacting of the first conductor and the second conductor and to abort the phase check in the event that the measured frequencies lie outside a predetermined frequency range.

8. phase test device according to claim 7, characterized by a device of the test circuit (9, 10) for determining the frequency change both during the contacting of the first conductor and the second conductor and for aborting the phase test in the event that the difference of two rates of frequency change is greater than a predetermined value.

9. phase test device according to claim 7 or 8, characterized by a device for calculating the result of the relationship between time and frequency compensation wheel based on measured frequencies.

10. phase test device according to one of claims 5 to 9, characterized in that the microcontroller (10) also forms the devices for frequency determination, for determining the frequency change rate and for calculating the best-fit line.